Process of making a knitted fabric



Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE PROCESS OF MAKING A KNITTED FABRIC New York No Drawing. Application April 26, 1934, Serial No. 722,508

2 Claims. (Cl. 66-202) The present'invention relates to a method of manufacturing knitted textile materials, and it particularly relates to a method of manufacturing silk stockings.

Knitting yarns, such as natural silk in gum, in being twisted and/or knitted sometimes have body-giving coatings which enable them to be subjected to textile processing operations in a most satisfactory manner. These body-giving materials, however, must be removed before the knitted fabric is finished. For example, silk hose' or stockings containing raw silk in gum ordinarily must be degummed in a solution of a relatively high alkalinity or high pH. To reduce the length of the finishing operation and to simplify such operation as much as possible, it is desirable in many instances to dye the fabric simultaneously with the degumming. However, the dyes so employed must necessarily have the property to dye or to combine with the silk under the chemical and physical conditions existing in such degumming bath or solution.

Many of the best dyestuffs for silk do 'not dye satisfactorily in solutions which are weakly or moderately alkaline, but require either a neutral or acid medium. Such dyestuffs are therefore of no practical use in the simultaneous degumming and dyeing of silk in alkaline solution.

It is an object of the present invention to so produce afabric and particularly a silk stock ing, preferably of natural silk in gum, in such a manner that the fabric may be most readily simultaneously degummed and dyed with any desirable dye, with relatively decreased expense and with an improved quality of the final fabric. 7

Other objects will appear during the course of the following specification.

By impregnating silk with a proteolytic enzyme preparation preparatory to twisting and knitting, the gum becomes so affected that its ultimate removal by treatment with solutions which are either acid, neutral or alkaline in reaction now becomes possible.

Simultaneous degumming and dyeing of silk so impregnated with proteolytic enzyme preparation is therefore not limited to the use of solutions of alkaline reaction alone and any dyestufi which is of practical value for silk dyeing purposes can be employed by simply adjusting the 50 reaction of the degumming bath to the pH most suitable for the particular dyestuff.

Among the preferred enzyme preparations are those prepared from plants and/or by the growth of certain bacteria, fungi, and other similar or- 55 ganisms.

It is an essential feature of the present invention that the natural silk in gum before being subjected to any textile operations, such as'twisting and knitting, be impregnated with the enzyme preparation without being degummed.

5 The degumming operation is only carried out long after the enzyme treatment, and is preferably carried out without further introduction of any proteolytic enzyme preparations after the goods have been finally knitted and are being subjected to, or about to be subjected to, finishing operations.

In the preferred procedure, the natural silk in yarn or skein form, is dipped into a bath of a temperature below 50 C., said bath containing in solution and/or in suspension the proteolytic enzyme preparation with which may be preferably combined the alkali metal salt or salts'of a high molecular weight fatty acid or fatty acids, or the alkali metal salt'of high molecular weight sulphuric or sulphonic acids, of aliphatic, aromatic, and alycyclic compounds of high molecular weight.

Among the compounds which may be used are sodium oleate, sodium palmitate, sodium stearate, sodium hexadecyl sulphonate, and so forth.

To this bath may'also be conveniently added an oil, such as a s'ulphonated oil or an unsulphonated oil, as for example, neats foot oil, Turkey red oil, raw vegetable oils, such as claim, and so forth.

The skein or yarn may be suspended in the soaking bath for a sufficient length of time to assure that the enzyme preparation and the other ingredients have thoroughly penetrated the gum in the silk, and at all times the temperature and pH should be so maintained that substantially no degumming action results.

This soaking may be carried out from 30 minutes to'sixteen hours, and it preferably should not be carried out for longer than 24 hours. The 40 skein or yarn after being so impregnated with the enzyme preparation is centrifuged so as to remove as much moisture as possible and then is thoroughly or partly dried before being subjected to further textile forming operations.

Various protease preparations may be used in carrying out the process, such as protease prepations derived from mioro-organisms which under suitable culture conditions develop proteolytic enzymes as, for instance, preparations derived from Aspergillus Oryza, from cultivation of bacteriaa, such as B. mesentericus or B. subtz'lis. Other suitable proteolytic enzymes may be used, such as papain, trypsin, or pepsin. Suitable mixtures of the above described enzymes may also be used.

As examples in carrying out the process, one may proceed as follows:

Example 1.100 pounds of raw silk are soaked from 30 minutes to 1 hour in a bath or solution consistingv of 400 pounds of water in which have been dissolved 50 pounds of the bacterial enzyme preparation, 1 pound of sodium sulfite for effecting a suitable pH, and 1 pound of sulfonated oil, this latter material being used to effect a better penetration, or as it is technically called, a wetting-out of the fibre, though it will be understood that other penetrants can be used for eifecting this wetting-out, such as a small amount of soap.

If the soaking period is increased the amount of enzyme may be decreased, as for example, with over-night soaking only half as much enzyme is required.

Other suitable pH regulators, for instance, sodium carbonate or bicarbonate, or a mixture thereof may be used instead of the sodium sulfite referred to.

Emulsions of common soaking oils, such as neats foot oil, may also be used in conjunction with enzymes.

The temperature at which this process is carried out may be advantageously varied with the time consumed in the operation, the nature or origin of the silk, the nature of the particular enzyme employed, and the presence of other constituents, such as pH regulators. However, we generally employ this process at room tempera ture, that is, from 60 to 85 F.

The silk is then removed from the enzyme bath and the adhering liquor is removed in any suitable manner, as by centrifuging, and after the centrifuging step the silk fibres are dried at a low temperature by an air blast or any other suitable method.

Earample 2.100 pounds of 13/15 japan white silk in the gum are soaked for 30 minutes at room temperature in 400 pounds of water solution containing 5 pounds of papain, 4 pounds of sulfonated oil, 0.05 pounds of potassium cyanide, and 2 pounds of mono-sodium phosphate. It is then centrifuged and air dried.

Example 3.100 pounds of 13/15 japan white silk in the gum are soaked for 30 minutes at room temperature in 400 pounds of water solution containing 5 pounds of pancreatin, and 1 pound of sodium sulfite and suitable penetrants and/or oils. It is then centrifuged and air dried.

After this treatment the various strands to make the knitting yarn may be twisted or thrown together and subsequently knitted to form a final knitted fabric or stocking. Where the yarn is composed of some strands of relatively high twist and other strands of relatively low twist, or substantially untwisted, the relatively high twist strands may be subjected to an impregnation with a greater concentration of the enzyme preparation or for a longer period to assure that the degumming or decoating of the relatively inaccessible fibres will take place at more nearly the same rate as the degumming of the relatively accessible fibres or strands.

To give an example, stockings composed of an enzyme-impregnated low twist natural silk in gum are placed in a dye bath containing direct and acid dyes in the following proportions:

60 dozen stockings 100 gallons of water 4 ounces Turkey red oil 2 pounds Glaubers salt.

A suitable mixture of direct and acid dyes to produce a light brown.

The resultant stockings are of most satisfactory softness and color and of particularly high quality.

The process of the present application is also particularly applicable to chiifon stockings which may or may not contain cotton in the top and feet, as for example, stockings in which the silk fibres have a twist of about turns to the inch. It is to be understood that the present invention is not only applicable to the simultaneous dyeing and degumming of knitted fabrics containing natural silk in gum, but also may be broadly adapted to the simultaneous dyeing and degu l-- ming of many other fabrics containing gum silk where a similar problem is presented.

The present application is a continuation in part of application Serial No. 606,286, filed April 19, 1932, and is similar in subject matter to the copending applications Serial Nos. 722,504 to 722,507, all filed April 26, 1934.

The present application is particularly directed to a knitted fabric or stocking fabric which may be simultaneously degummed and dyed.

What is claimed is:

1. A process of making a knitted fabric capable of being simultaneously dyed and degurnmed in acid, neutral and alkaline media, which comprises impregnating yarn composed of natural silk in gum with a proteolytic enzyme preparation, while leaving the gum on the yarn without disadvantageously afiecting its body giving properties, then twisting the yarn and finally knitting the yarn.

2. A process of making knitted stockings capable of being simultaneously dyed and degummed in acid, neutral and alkaline media, which com prises impregnating yarn composed of natural silk in gum with a proteolytic enzyme preparation, while leaving the gum on the yarn without disadvantageously affecting its body giving properties, then twisting the yarn and finally knitting the yarn to make said stockings.

LEO WALLERSTEIN. ROWLAND A GALE. THOMAS G. HAWLEY, JR. 

